Authorities in Northern California said Tuesday that a woman and her boyfriend charged with killing her 3-year-old daughter stored the girl's body in a suitcase and inside a freezer.

Sara Krueger and her boyfriend, Ryan Scott Warner both of Napa, put little Kayleigh Slusher's body in a suitcase and then placed her body in a freezer, Napa Police Capt. Jeff Troendly said.

"Investigators learned through interviews with the suspects that the girl's body was kept in a suitcase at one point and then a freezer," Troendly said. "We believe that they are responsible for the death of Kayleigh Slusher."

Krueger, 23 and Warner, 26, were charged with murder and assault on a child resulting in death, Napa County District Attorney Gary Lieberstein announced Tuesday.

The couple was scheduled to appear in court in the afternoon. Each could spend up to 25 years to life in prison, if convicted.

Police found Kayleigh's lifeless body in her bed while conducting a welfare check at Krueger's apartment in Napa on Saturday. Witnesses had seen Krueger and Warner leaving the apartment with some luggage a few hours earlier, Napa Police Lt. Debbie Peecook said.

On Sunday, the couple was arrested at San Francisco Bay Area Rapid Transit station in El Cerrito after being spotted at a nearby restaurant, Peecook said.

The girl showed signs of having been sexually assaulted and blunt-force trauma, police said. Krueger and Warner were not charged with sexual assault, Troendly said.

Police have visited the couple's apartment numerous times in the past year in response to calls from neighbors, but no arrests had been made, he said.

Officers last visited the apartment on Jan. 29 to conduct a welfare check on the girl, Troendly said. Everything appeared to be all right as police conducted a field sobriety test on the couple and interviewed the girl, he added.

"There was no indication that would be in danger in that household," Troendly said. "When you hear a case like this, it's shocking and disheartening.

"Our community is being impacted by how this could happen to someone at such a young age. It's mindboggling."